Permissions for study management
changes in permission rules:
- with ADMIN role, studies can be managed even if not explicitly member of the study
- with ADMIN and RESEARCHER role, data can be accessed without explicitly being a member of the study
-> RESEARCHERs only, still need to be added as study member
These changes are intended to simplify setup for use-cases with "single purpose studies", where a more fine-granular permission setting is not necessary.